KVM would like to provide x2APIC interface to a guest without emulating
interrupt remapping device. The reason KVM prefers guest to use x2APIC
is that x2APIC interface is better virtualizable and provides better
performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Included patch changes x2APIC enabling logic to enable it even if IR
initialization failed, but kernel runs under KVM and no apic id is
greater than 255 (if there is one spec requires BIOS to move to x2apic
mode before starting an OS).
-v2: fix build
-v3: fix bug causing compiler warning
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Sheng Yang <sheng@linux.intel.com>
Cc: "avi@redhat.com" <avi@redhat.com>
LKML-Reference: <20090720122417.GR5638@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Clear TS in irq_ts_save() when in an atomic section
x86: Detect use of extended APIC ID for AMD CPUs
x86: memtest: remove 64-bit division
x86, UV: Fix macros for multiple coherency domains
x86: Fix non-lazy GS handling in sys_vm86()
x86: Add quirk for reboot stalls on a Dell Optiplex 360
x86: Fix UV BAU activation descriptor init
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, nmi: Use predefined numbers instead of hardcoded one
x86: asm/processor.h: remove double declaration
x86, mtrr: replace MTRRdefType_MSR with msr-index's MSR_MTRRdefType
x86, mtrr: replace MTRRfix4K_C0000_MSR with msr-index's MSR_MTRRfix4K_C0000
x86, mtrr: remove mtrr MSRs double declaration
x86, mtrr: replace MTRRfix16K_80000_MSR with msr-index's MSR_MTRRfix16K_80000
x86, mtrr: replace MTRRfix64K_00000_MSR with msr-index's MSR_MTRRfix64K_00000
x86, mtrr: replace MTRRcap_MSR with msr-index's MSR_MTRRcap
x86: mce: remove duplicated #include
x86: msr-index.h remove duplicate MSR C001_0015 declaration
x86: clean up arch/x86/kernel/tsc_sync.c a bit
x86: use symbolic name for VM86_SIGNAL when used as vm86 default return
x86: added 'ifndef _ASM_X86_IOMAP_H' to iomap.h
x86: avoid multiple declaration of kstack_depth_to_print
x86: vdso/vma.c declare vdso_enabled and arch_setup_additional_pages before they get used
x86: clean up declarations and variables
x86: apic/x2apic_cluster.c x86_cpu_to_logical_apicid should be static
x86 early quirks: eliminate unused function
Booting a 32-bit kernel on Magny-Cours results in the following panic:
...
Using APIC driver default
...
Overriding APIC driver with bigsmp
...
Getting VERSION: 80050010
Getting VERSION: 80050010
Getting ID: 10000000
Getting ID: ef000000
Getting LVT0: 700
Getting LVT1: 10000
Kernel panic - not syncing: Boot APIC ID in local APIC unexpected (16 vs 0)
Pid: 1, comm: swapper Not tainted 2.6.30-rcX #2
Call Trace:
[<c05194da>] ? panic+0x38/0xd3
[<c0743102>] ? native_smp_prepare_cpus+0x259/0x31f
[<c073b19d>] ? kernel_init+0x3e/0x141
[<c073b15f>] ? kernel_init+0x0/0x141
[<c020325f>] ? kernel_thread_helper+0x7/0x10
The reason is that default_get_apic_id handled extension of local APIC
ID field just in case of XAPIC.
Thus for this AMD CPU, default_get_apic_id() returns 0 and
bigsmp_get_apic_id() returns 16 which leads to the respective kernel
panic.
This patch introduces a Linux specific feature flag to indicate
support for extended APIC id (8 bits instead of 4 bits width) and sets
the flag on AMD CPUs if applicable.
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: <stable@kernel.org>
LKML-Reference: <20090608135509.GA12431@alberich.amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently, when x2apic is not enabled, interrupt remapping
will be enabled in init_dmars(), where it is too late to remap
ioapic interrupts, that is, ioapic interrupts are really in
compatibility mode, not remappable mode.
This patch always enables interrupt remapping before ioapic
setup, it guarantees all interrupts will be remapped when
interrupt remapping is enabled. Thus it doesn't need to set
the compatibility interrupt bit.
[ Impact: refactor intr-remap init sequence, enable fuller remap mode ]
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Weidong Han <weidong.han@intel.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: allen.m.kay@intel.com
Cc: fenghua.yu@intel.com
LKML-Reference: <1239957736-6161-4-git-send-email-weidong.han@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Shouldn't call ack_apic_edge() in ir_ack_apic_edge(), because
ack_apic_edge() does more than just ack: it also does irq migration
in the non-interrupt-remapping case. But there is no such need for
interrupt-remapping case, as irq migration is done in the process
context.
Similarly, ir_ack_apic_level() shouldn't call ack_apic_level, and
instead should do the local cpu's EOI + directed EOI to the io-apic.
ack_x2APIC_irq() is not neccessary, because ack_APIC_irq() will use MSR
write for x2apic, and uncached write for non-x2apic.
[ Impact: simplify/standardize intr-remap IRQ acking, fix on !x2apic ]
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Weidong Han <weidong.han@intel.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: allen.m.kay@intel.com
Cc: fenghua.yu@intel.com
LKML-Reference: <1239957736-6161-3-git-send-email-weidong.han@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: refactor, speed up and robustize code
In case if apic was disabled by kernel option
or by hardware limits we can use dummy operations
in apic->write to simplify the ack_APIC_irq() code.
At the lame time the patch fixes the missed EOI in
do_IRQ function (which has place if kernel is compiled
as X86-32 and interrupt without handler happens where
apic was not asked to be disabled via kernel option).
Note that native_apic_write_dummy() consists of
WARN_ON_ONCE to catch any buggy writes on enabled
APICs. Could be removed after some time of testing.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090412165058.724788431@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, no code changed
- syscalls.h update declarations due to unifications
- irq.c declare smp_generic_interrupt() before it gets used
- process.c declare sys_fork() and sys_vfork() before they get used
- tsc.c rename tsc_khz shadowed variable
- apic/probe_32.c declare apic_default before it gets used
- apic/nmi.c prev_nmi_count should be unsigned
- apic/io_apic.c declare smp_irq_move_cleanup_interrupt() before it gets used
- mm/init.c declare direct_gbpages and free_initrd_mem before they get used
Signed-off-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
interrupt remapping must be enabled before enabling x2apic, but
interrupt remapping doesn't depend on x2apic, it can be used
separately. Enable interrupt remapping in init_dmars even x2apic
is not supported.
[dwmw2: Update Kconfig accordingly, fix build with INTR_REMAP && !X2APIC]
Signed-off-by: Weidong Han <weidong.han@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This patch enables suspend/resume for interrupt remapping. During suspend,
interrupt remapping is disabled. When resume, interrupt remapping is enabled
again.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Partial revert of commit 129d8bc828
titled 'x86: don't compile vsmp_64 for 32bit'
Commit reverted to compile vsmp_64.c if CONFIG_X86_64 is defined,
since is_vsmp_box() needs to indicate that TSCs are not synchronized, and
hence, not a valid time source, even when CONFIG_X86_VSMP is not defined.
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: shai@scalex86.org
LKML-Reference: <20090324061429.GH7278@localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: optimize APIC IPI related barriers
Uncached MMIO accesses for xapic are inherently serializing and hence
we don't need explicit barriers for xapic IPI paths.
x2apic MSR writes/reads don't have serializing semantics and hence need
a serializing instruction or mfence, to make all the previous memory
stores globally visisble before the x2apic msr write for IPI.
Add x2apic_wrmsr_fence() in flush tlb path to x2apic specific paths.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "steiner@sgi.com" <steiner@sgi.com>
Cc: Nick Piggin <npiggin@suse.de>
LKML-Reference: <1237313814.27006.203.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, paranoia
We were not clearing the local APIC in clear_local_APIC() in the
presence of x2apic. Fix it.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Impact: cleanup
- rename apic->wakeup_cpu to apic->wakeup_secondary_cpu, to
make it apparent that this is an SMP-only method
- handle NULL ->wakeup_secondary_cpus to mean the default INIT
wakeup sequence - this allows simplification of the APIC
driver templates.
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix
wakeup_secondary_cpu_via_init(), the default platform method for
booting a secondary CPU, is always used on UP due to probe_32.c,
if CONFIG_X86_LOCAL_APIC is enabled but SMP is off.
So provide a UP wrapper inline as well.
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
that is only needed when CONFIG_X86_VSMP is defined with 64bit
also remove dead code about PCI, because CONFIG_X86_VSMP depends on PCI
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
x86_quirks->update_apic() calling looks crazy. so try to remove it:
1. every apic take wakeup_cpu member directly
2. separate es7000_apic to es7000_apic_cluster
3. use uv_wakeup_cpu directly
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If BIOS hands over the control to OS in legacy xapic mode, select
legacy xapic related ops in the early apic probe and shift to x2apic
ops later in the boot sequence, only after enabling x2apic mode.
If BIOS hands over the control in x2apic mode, select x2apic related
ops in the early apic probe.
This fixes the early boot panic, where we were selecting x2apic ops,
while the cpu is still in legacy xapic mode.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Now that all APIC code is consolidated there's nothing 'gen' about
apics anymore - so rename 'struct genapic' to 'struct apic'.
This shortens the code and is nicer to read as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Reduce the number of include files to worry about.
Also, most of the users of APIC facilities had to
include genapic.h already, which embedded apic.h,
so the distinction was meaningless.
[ include apic.h from genapic.h for compatibility. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
make it simpler, don't need have one extra struct.
v2: fix the sgi_uv build
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
so could deselect x2apic
and INTR_REMAP will select x2apic
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Remove the 32-bit subarchitecture support code.
All subarchitectures but Voyager have been converted. Voyager will be
done later or will be removed.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, reduce kernel size a bit, avoid sparse warning
Fixes sparse warning:
arch/x86/kernel/apic.c:270:5: warning: symbol 'x2apic_icr_read' was not declared. Should it be static?
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Impact: cleanup, reduce kernel size a bit, avoid sparse warning
Fixes sparse warning:
arch/x86/kernel/apic.c:103:5: warning: symbol 'disable_x2apic' was not declared. Should it be static?
Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: really halt all CPUs on halt
Function machine_halt (resp. native_machine_halt) is empty for x86
architectures. When command 'halt -f' is invoked, the message "System
halted." is displayed but this is not really true because all CPUs are
still running.
There are also similar inconsistencies for other arches (some uses
power-off for halt or forever-loop with IRQs enabled/disabled).
IMO there should be used the same approach for all architectures OR
what does the message "System halted" really mean?
This patch fixes it for x86.
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:
a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
